Abstract:
The purpose of this study was to assess the value of the
ventilation study in the diagnosis of acute pulmonary
embolism using a new automated method. Either perfusion
scintigrams alone or two different combinations of
ventilation/perfusion scintigrams were used as the only
source of information regarding pulmonary embolism. A
completely automated method based on computerised image
processing and artificial neural networks was used for the
interpretation.Methods: Three artificial neural networks
were trained for the diagnosis of pulmonary embolism. Each
network was trained with 18 automatically obtained features.
Three different sets of features originating from three sets
of scintigrams, were used. One network was trained using
features obtained from each set of perfusion scintigrams,
including six projections. The second network was trained
using features from each set of (joint) ventilation and
perfusion studies in six projections. A third network was
trained using features from the perfusion study in six
projections combined with a single ventilation image from the
posterior view. A total of 1087 scintigrams from patients
with suspected pulmonary embolism were used for network
training. The test group consisted of 102 patients who had
performed both a scintigram as well as pulmonary angiography.
Performances in the test group were measured as area under
the receiver operation characteristic curve.Results: The performance of the neural
network interpreting perfusion scintigrams alone was 0.79
(95% confidence limits 0.71-0.86). When one ventilation image
(posterior view) was added to the perfusion study, the
performance was 0.84 (0.77-0.90). The increase was
statistically significant (p<0.01). The performance
increased to 0.87 (0.81-0.93) when both the perfusion and
ventilation studies were used and also this increase in
performance was statistically significant (p<0.01).Conclusions: The automated method presented
here for the interpretation of lung scintigrams shows a
significant increase in performance when one or all
ventilation images are added to the six perfusion images.
Thus, the ventilation study has a significant role in the
diagnosis of acute lung embolism.